Microvesicles (MVs) are phospholipid vesicles released into the circulation by cells, which have recently emerged as a new diagnostic biomarker. Elevated level of MVs has been reported in various malignancies, including cardiovascular diseases, diabetes, and inflammation; MVs also appear to play an integral role in the erythrocyte aging process. However, a major barrier to advancing our knowledge of MV biology, and thus fully harnessing their clinical potential, has been the lack of accurate and standardized methods for MV analysis. We have recently developed a new, nanotechnology-based diagnostic platform termed DMR (diagnostic magnetic resonance). By employing principles of nuclear magnetic resonance (NMR), the DMR device measures the transverse relaxation of samples, whereby biological targets are labeled with molecular-specific magnetic nanoparticles (MNPs). By systematically developing optimized MNPs and chip-based miniature NMR systems, the DMR technology has now significantly advanced so as to provide sensitive, point-of-care molecular analyses of cells. Building upon these achievements, the overall goal of this proposal is to adapt and further advance the DMR platform for rapid detection and multiplexed profiling of MVs directly from whole blood. We will specifically focus on the following aims. In Aim 1, we will synthesize new magnetic nanoagents and assay methods that will allow highly efficient and selective MNP-labeling of MV targets. In Aim 2, we will implement a miniaturized NMR system integrated with sophisticated microfluidics. This system will be designed to enable MV analysis to be performed entirely on a single chip; it will isolate MVs directly from whole blood, label MVs with MNPs, and perform NMR measurements on the targeted MVs. In Aim 3, both the optimized nanoagents and device will be applied to the detection and comprehensive profiling of erythrocyte-derived MVs in blood products. This study will advance our understanding of the biology of blood aging, which could lead to improved blood product quality and transfusion safety. We envision a broad diagnostic potential for the proposed DMR-MV technology in both the life sciences and in clinical practice. By facilitating the rapid and quantitative molecular analysis of MVs from different cellular origins, this technology could enable early disease detection and treatment monitoring. In turn, this could expedite advances in creating personalized treatment by providing valuable information on the cellular/molecular signatures of individual patients.